License plate readers spark privacy, public safety debate

Nov. 20, 2013
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A police officer prepares to go out on patrol using a license plate reader, which photographs license plates and then compares them with those in a database of stolen vehicles. Some states are considering limits on how long police can keep the data. / AP

by Maggie Clark, Pew/Stateline Staff Writer

by Maggie Clark, Pew/Stateline Staff Writer

Police have used cameras that read the license plates on passing cars to locate missing people in California, murderers in Georgia and hit-and-run drivers in Missouri.

The book-sized license plate readers (LPRs) are mounted on police cars, road signs or traffic lights. The images they capture are translated into computer-readable text and compiled into a list of plate numbers, which can run into the millions. Then police compare the numbers against the license plates of stolen cars, drivers wanted on bench warrants or people involved in missing person cases.

Privacy advocates don't object to police using LPRs to catch criminals. But they are concerned about how long police keep the numbers if the plates don't register an initial hit. In many places there are no limits, so police departments keep the pictures-tagged with the date, time, and location of the car-indefinitely.

The backlash against LPRs began in earnest this year, as three more states limited law enforcement use of the systems and in some cases banned private companies from using the systems, for example, to track down cars for repossession. So far, five states limit how the cameras are used, and the American Civil Liberties Union anticipates that at least six other states will debate limits in the upcoming legislative session.

In New Hampshire, police and private companies (with the exception of the tolling company EZ Pass) are forbidden from using license plate readers. Utah requires police to delete license plate data nine months after collection. In Vermont, the limit is 18 months and in Maine it is three weeks. Arkansas police have to throw out the plate numbers after 150 days and parking facilities are the only private companies allowed to use the technology.

"It's been surprising to find out how license plate readers are being used and how long the data is being kept," said Michigan state Rep. Sam Singh, a Democrat, who is sponsoring legislation to limit police in his state from keeping license plate numbers for longer than 48 hours. Police are using the cameras in a handful of Michigan cities, including Detroit and East Lansing.

Singh's legislation would also make the license plate data exempt from public records requests so that, for example, divorce attorneys couldn't request license plate reader data to confirm where a spouse was at a particular time. The bill, which is still in committee, also would limit how private companies can use license plate readers to track down cars for repossession.

"We just fundamentally believe that Americans don't need to be watched unless there's probable cause of wrongdoing," said Shelli Weisberg, legislative director for the Michigan ACLU, which supports Singh's bill. "We don't need a 'just in case' database. That just turns democracy and our sense of due process on its head."

NSA fallout

The debate over license plate readers and other law-enforcement technologies is a local expression of a national wariness about government spying in the wake of revelations about the National Security Agency's far-reaching data collection on ordinary citizens across the world.

"People are saying, 'I can't control the NSA, but I can rein in what local law enforcement agencies are collecting,'" said Allie Bohm, an advocacy and policy strategist at the ACLU. Last July, the ACLU released a report warning about the lack of policies for license plate reader programs. The group also has promoted model legislation to limit how long police can keep license plate data.

For proponents of the technology, the timing of the NSA leaks couldn't have been worse. "I would hate to see that because of bad timing, a great technology is banned or didn't rise to the level it could have," said Todd Hodnett, the founder and chairman of Digital Recognition Network, a license plate reader manufacturer which sells the cameras to private companies, including towing firms, banks and insurance companies. An LPR system, which typically includes four cameras, costs between $15,000 and $18,000.

Lumping license plate readers in with the NSA surveillance system creates a false equivalency, according to Hodnett. "The NSA revelations have created an environment that has people on edge, but it's unfortunate and quite scary that someone could compare listening to a phone call to photographing a publicly visible license plate," he said.

Hodnett also argued the focus on data limits is misplaced, because matching a license plate to a person's DMV records or driver's license record is a two-step process governed by the Driver's Privacy Protection Act passed by Congress in 1994. When law enforcement officers want to make a query of DMV records using a license plate number, they have to show a "permissible purpose," which includes public safety, motor vehicle theft, court proceedings or notifying owners of towed or impounded vehicles.

Until a license plate number is matched to DMV data, it's as anonymous to officers as it is to a person standing on a street corner. That two-step process is what keeps the technology from infringing on privacy, said Robert Stevenson, the executive director of the Michigan Association of Chiefs of Police and the retired police chief of Livonia, Mich.

"There's an additional step that has to be taken to find out who the drivers are," said Stevenson. "People's pictures and names don't just pop up when they drive past license plate readers."

The U.S. Supreme Court and multiple federal courts have affirmed there is no expectation of privacy for a publicly visible license plate. Hodnett is building a case to argue that prohibiting license plate readers from taking photographs of publicly visible license plates is a violation of the First Amendment.

Tracking the Marathon bombers

In the hunt for the Boston Marathon bombers, police used license plate reader data to establish where the Tsarnaev brothers had traveled and where they might be headed, based on places they'd already been. Police used license plate readers to track Dzokhar Tsarnaev to Watertown, Mass., where police found him hiding in a boat in a resident's backyard.

Even though LPR data was used in that investigation, Watertown's state representative is pursuing legislation to limit license plate readers. Under Democratic Rep. Jonathan Hecht's legislation, police would be required to delete license plates collected after 48 hours, but they could hang on to data longer if it was specifically part of a criminal investigation, like the search for Tsarnaev.

"Public safety is very important and we want to use new this technology for safety," said Hecht. "But as has been true throughout our history, public safety has to be balanced against other important privacy values. In wake of the revelations about the NSA, people are concerned that we're letting technology get away from us."

Stateline is a nonpartisan, nonprofit news service of the Pew Charitable Trusts that provides daily reporting and analysis on trends in state policy.